Police have investigated almost 300 accusations of offences within South Yorkshire’s prisons and youth offenders centres in the last three years.

Figures obtained by the Star through a Freedom of Information Request reveal murder, sexual assault and grievous bodily harm are among recent accusations made.

The data comes from HMP & YOI Doncaster, HMP & YOI Moorland and Hatfield, and HMP Lindholme, all in Doncaster.

A former prison officer was jailed in May for misconduct in a public office after it emerged she had a relationship with a prisoner. An investigation found that Dawn Sheard, 46, had sex with the inmate while on duty at Doncaster Prison.

Fifty-seven individuals were accused of physical violence such as murder, robbery, assault, and inflicting grievous bodily harm, totalling 19.6 per cent of the accusations.

Julian Maylor and Reiss Comrie, both 24 at the time, were cleared of killing Michael Hennessy in Lindholme Prison, Doncaster, in December 2013, by a jury at Sheffield Crown Court in August 2014.

The number of deaths per year in UK prisons rose from 198 to 257 from 2010 to 2015, according to figures released by the Ministry of Justice earlier this year.

A total of 291 individuals are accused of 278 offences in South Yorkshire’s prisons and young offenders centres from August 2013 to August 2016.

Senior Lecturer in Criminology at Sheffield Hallam University, Dr Jamie Irving, said these recorded offences are likely to account for a small proportion of actual crimes committed.

“Much like any officially recorded crime, the ‘dark figure’ of the bottom of the iceberg that sits below the water line is much greater.”

Most alleged offences in South Yorkshire’s prisons related to possessing or smuggling in prohibited items.

There were 96 accusations of smuggling prohibited articles into or out of prison and 83 accusations of possessing such items making up 61.5 per cent of the total accusations.